The Internet of Things (IoT) is a vision of the future where everything that can benefit from a connection will be connected. Cellular technologies are being developed or evolved to play an indispensable role in the IoT world, particularly for machine-type communication (MTC). MTC is characterized by lower demands on data rates than, for example, mobile broadband, but with more stringent requirements on low cost device design, better coverage, and the ability to operate on batteries for years without charging or replacing the batteries. To meet the IoT design objectives, the 3rd Generation Partnership Project (3GPP) has standardized Narrowband IoT (NB-IoT) in 3GPP Release 13, which has a system bandwidth of 180 kHz and targets improved coverage, long battery life, low complexity communication design, and network capacity that is sufficient for supporting a massive number of devices.
Support for geolocation positioning in Long Term Evolution (LTE) was introduced in 3GPP Release 9. This enhancement enables operators to retrieve position information for location-based services and to meet regulatory emergency call positioning requirements. To further increase the market impact of NB-IoT, 3GPP Release 14 includes improved narrowband support for positioning, which is primarily driven by the need for the location-based services and emergency call positioning. This enhancement will be designed to maintain the ultra-low cost and complexity of an NB-IoT user equipment (UE) where appropriate, as well as the coverage and capacity of the NB-IoT network.
Geolocation positioning in LTE is supported by the architecture in FIG. 1, with direct interactions between a UE and a location server (e.g., Evolved Serving Mobile Location Server (E-SMLC)) is via the LTE Positioning Protocol (LPP). Moreover, there are also interactions between the location server and the evolved Node B (eNodeB) via the LPP protocol, to some extent supported by interactions between the eNodeB and the UE via the Radio Resource Control (RRC) protocol.
Various positioning techniques are considered in LTE, including Enhanced Cell ID, Assisted Global Navigation Satellite System (GNSS), Observed Time Difference of Arrival (OTDOA), Uplink Time Difference of Arrival (UTDOA). The Enhanced Cell ID technique essentially uses cell identification (ID) information to associate the UE to the serving area of a serving cell, and then uses additional information to determine a finer granularity position. The Assisted GNSS technique uses GNSS information retrieved by the UE that is derived based on assistance information provided to the UE from an E-SMLC. The OTDOA technique uses estimates by the UE of the time difference of reference signals from different localized base stations that are then sent to the E-SMLC for multilateration. The UTDOA technique, introduced in 3GPP Release 11, requests that the UE transmits a specific waveform that is then detected by multiple location measurement units (e.g., eNB) at known positions, with the measurements forwarded to an E-SMLC for multilateration.
In LTE, the basic concept of UTDOA is that a positioning server (e.g., an E-SMLC) requests the position of a UE, which then triggers the UE to transmit a reference signal received by a multitude of time-synchronized nodes in a network. For LTE, UTDOA uses the Sounding Reference Signal (SRS) as the reference signal to be transmitted by the UE and then received by the multitude of time-synchronized nodes. The reception of the transmitted reference signal at the network side is handled by a Location Measurement Unit (LMU), which is special-purpose equipment typically co-located with the eNB. Upon receiving the transmitted reference signal, each LMU can estimate a time of arrival (TOA) of the transmitted reference signal, calculate the Time Difference Of Arrival (TDOA), and forward the TDOA to the positioning server. Based on the TDOA provided by each LMU and the known position of each LMU, the positioning server can estimate the position of the UE by using multilateration techniques.
However, the UTDOA technique has drawbacks for NB-IoT. For instance, SRS signals that are used for UTDOA in an LTE network are not available for an NB-IoT network. Further, an NB-IOT network may not include LMU-type equipment due to cost limitations. In addition, there are advantages to upgrading an LTE or NB-IoT network to a new release (e.g., 3GPP Release 14) via a software update without having to add new hardware.
Accordingly, there is a need for techniques to improve determining a position of a wireless device (e.g., UE) using, for instance, UTDOA. Furthermore, other desirable features and characteristics of the present disclosure may become apparent from the subsequent detailed description and claims, taken in conjunction with the accompanying figures and the foregoing technical field and background.
The Background section of this document is provided to place embodiments of the present disclosure in technological and operational context, to assist those of skill in the art in understanding their scope and utility. Unless explicitly identified as such, no statement herein is admitted to be prior art merely by its inclusion in the Background section.